Gravity and God: A personal reflection on gravitational waves

The collision of two black holes – an event detected for the first time ever by the Laser Interferometer Gravitational-Wave Observatory, or LIGO – is seen in this still from a computer simulation (Credit: cc by Simulating eXtreme Spacetimes)

Editor’s note: Covalence’s Theological Editor George Murphy offers up his commentary this month on one of the most fascinating current discoveries from the world of physics as Editor Susan Barreto takes a hiatus. Her regular column will return in the April edition.

Einstein’s general relativity theory predicted gravitational waves 100 years ago but it took nearly 50 years before Joseph Weber of the University of Maryland began a serious observational search for them. He eventually reported detection of these waves, generating skepticism from other physicists. At a relativity conference in 1969 I was in a conversation about this and there was some joking about what the first gravitational wave message from space would be. Someone suggested “In the beginning was the Word…”

Skepticism at that time was justified. Weber’s antenna, while good in principle, didn’t have the necessary sensitivity. Another half century passed before this year’s news that gravitational waves had been detected. They came from colliding black holes roughly a billion light years away, and were not a message directly from God.

But when important scientific discoveries get on the nightly news, questions are often raised about their religious significance — think of early space exploration, the cloning of the sheep Dolly or recent detection of the so-called “God particle.”   So do gravitational waves have any theological significance?

The Nicene Creed says that God is the maker “of all that is, seen and unseen,” so anything science finds out about the world might be of interest for theology.  But discoveries differ in significance and importance. When it was believed that God created all present biological kinds a few thousand years ago, discoveries about biological evolution and the earth’s age raised serious religious questions and required rethinking of some aspects of traditional theologies. I don’t see gravitational waves having that effect. But they do deserve theological reflection for at least a couple of reasons.

We ought to reflect first on what the discovery was and how it coheres with our understanding of creation. The Bible presents a picture of a creation intended from the beginning to change. God did not create the world in time but with time, as Augustine said. It was not static perfection but a cosmos directed toward a goal — the great Sabbath, the kingdom of God and the union of all things in Christ.

And few things about our present scientific knowledge of the world are clearer than that it is a world of change. From the dance of quantum fields at the heart of matter through the processes of biological evolution to the expansion of the universe, creation is dynamic.

For two millennia it was generally assumed that the geometry of Euclid was the only possible one, and that it gave an accurate description of the space we inhabit. Newton shared this belief, basing his system of mechanics on the assumptions of an absolute space and an absolute time. They were absolute in the sense that they were unaffected by matter and its motions within them. In the nineteenth century it was realized that Euclid’s geometry was not the only possibility and non-Euclidean geometries were developed.  Einstein found that he could exploit these mathematical discoveries to develop a theory of gravitation superior to that of Newton.

Einstein made use of a four-dimensional unification of space and time, and this space-time was not absolute. His equations described not just changes in positions of material bodies over time but changes of space-time itself. The geometry of the universe obeys dynamical laws! In particular, there could be gravitational waves, ripples of space-time curvature moving at the speed of light.  These ripples strain material bodies they pass through, and that is how they can be detected.

Thus in general relativity as Einstein conceived it, the cosmos at its most fundamental level is dynamic. Other confirmations of the theory had already shown this, but the detection of gravitational waves seems to be an especially dramatic illustration of this dynamic character of the world.

It seems to be that the geometry of space changes from moment to moment. But if we could have what some would call a “God’s eye view” of the whole of space-time, everything would look frozen. We would not see a particle moving from one point to another but its “world line” stretching from the remote past to the remote future. There is no becoming, only being.

This “block universe” has been the common view of workers in general relativity, but some other physicists are not so happy with it. Does general relativity have to be cast in this way? Given what I said above about the Christian understanding of a creation intended to have real change and a real history, perhaps theologians should be encouraging physicists to explore other ways of seeing Einstein’s theory.

This should not obscure the fact that Einstein’s theory has had a run of successful predictions, culminating in the detection of gravitational waves. This is especially impressive because when he began his work on gravitation there was no compelling observational demand to modify Newton’s law of gravitation. General relativity was a theoretical development par excellence. While insisting that observations must be the final test of a theory, Einstein believed that “pure thought” was, in a sense, able to come to a knowledge of physical reality. Our human reason is in some basic way in accord with the reason that pervades the universe.

And Christians can say that that is because our human reason is in accord with the Logos, the Reason or Word through whom all things were made. In one way the prediction of gravitational waves, like the successes of other scientific theories, does carry the message that “In the beginning was the Word….”

George Murphy received his Ph.D. in physics from Johns Hopkins for work on general relativity in 1972.  He taught at Westminster College (PA), The University of Western Australia and Luther College and did research for eleven years before entering Wartburg seminary. Ordained in 1983, he has served as a pastor in Lutheran and Episcopal congregations. His first article on theology and science was published in 1977 and he has since published six books and numerous articles and continues to speak and lead workshops in this area. His most recent book, Models of Atonement: Speaking about Salvation in a Scientific World (Lutheran University Press, 2013), discusses ways of understanding the saving work of Christ in an evolving world.